Reichhelm, Feenstra Kuiper and Di Felice all give Dion M. Martinez. Kingston, in reviewing The Steinitz Papers by Landsberger, gives Aristide Martínez. The Dec. 1883 issue of the Chess Monthly gives a partial result +5-0=1 for Steinitz, so the match presumably ended in Dec. 1883. Elo gives a combined result of 21.5-3.5 for Steinitz over the years 1882-1883, which matches other sources that give +7-0=0 and +3-1=3 in 1882 and +9-0=2 in 1883 for a total of 21.5-3.5.